Integrated drying and incineration of wet sewage sludge in combined bubbling and circulating fluidized bed units

•An original integrated drying and incineration technique is proposed.•Sewage sludge can be dried and incinerated well in only one system.•Experimental results show that the technique is a feasible way for sludge disposal.•The technique has several advantages compared with other techniques.

An original integrated drying and incineration technique is proposed to dispose of sewage sludge with moisture content of about 80% in a circulating fluidized bed. This system combines a bubbling fluidized bed dryer with a circulating fluidized bed incinerator. After drying, sewage sludge with moisture less than 20% is transported directly and continuously from the fluidized bed dryer into a circulating fluidized bed incinerator. Pilot plant results showed that integrated drying and incineration is feasible in a unique single system. A 100 t/d Sewage Sludge Incineration Demonstration Project was constructed at the Qige sewage treatment plant in Hangzhou City in China. The operational performance showed that the main operation results conformed to the design values, from which it can be concluded that the scale-up of this technique is deemed both feasible and successful.